Definitions

• Resource Record: structured data associated with names / nodes
  • format: owner ttl class type rdata
  • example: www.example.com 3600 IN A 192.0.2.127
• owner / name:
  • a node in the domain name tree
  • consists of a sequence of labels
  • format: node.zone.tld.
    • the right most label is null, aka the root
    • the 2nd from right is the top level domain
    • the 3rd from right is the [organizational] domain name (usually)
• label: character strings between the dots in a domain name
• ttl: time to live
  • how long to cache this DNS resource record
• class: IN, internet.
• type: the type of rdata that follows
  • examples: A, MX, SOA, PTR
• rdata: resource data. The contents vary widely by RR type
  • examples: A records have an address, CNAME records bear a cname target, NS records point to nameservers (nsdname).